Some users have had success using the lg bluetooth rolly keyboard but this is not officially supported.
Lg tv not connecting to cable box.
Once the box has rebooted turn the tv on and use the lg remote s input button to select hdmi 1.
Disconnect the cable box from power for 10 seconds to reboot it then plug it back in.
Simply connect your usb cable s to any available usb ports on the tv.
Unplug the power to the external device for 30 seconds.
Press the smart button on the remote control and select settings option set the universal control on the tv menu press wheel or enter to continue.
Change the tv to the new hdmi input to see if the issue.
Check that the external device is connected to the tv with an hdmi cable and is powered and switched on.
Now please try this.
Bluetooth mice and keyboards are not supported.
If your remote has an input source button press it and choose the input from the list that matches where your device is connected.
Perform the following steps if the no signal message remains.
If your remote does not have an input source button press the home button then look in the upper right corner of the tv for the input icon and click it.
Make sure the other end is secure in the cable box.